@Megalobronia
Luna, Stygian, and Tempest, for instance, were all drawn in by dark power, but they themselves never started out as bad guys and just needed the light shone on them again, so to speak.
Same with Starlight Glimmer, just without the “dark power” part. Just her insane personality that needed sorting out.
As for those like Storm King, Tirek, and Chrysalis, they didn’t like, have anything happen to them that needed working out, they were just card carrying bad guys and loving it.
If I had to guess to something I would have wanted seen different, I would wager Lightning Dust could have used a full reformation, but I’m not upset with what we got with her, at least.